As a known art for an output shaft supporting structure for automatic transmission, a structure for rotatably supporting an output shaft includes a first ball bearing disposed between the inner peripheral surface of a casing which covers a main body of the automatic transmission and the outer peripheral surface of an output shaft, and a second ball bearing disposed between the inner peripheral surface of an extension housing and the outer peripheral surface of the output shaft. (“MANUAL FOR TOYOTA NEW MODEL LAND CRUISER Part Number 61569” TOYOTA MOTOR COOPERATION SERVICE DIVISION, Jan. 17, 1990, The forth chapter, Underbody, P.16)
In the above identified known art, inclined rotation of the output shaft is prevented as much as possibly by setting an axial distance between the first ball bearing and the second ball baring relatively larger. The inclined rotation means that the output shaft rotates inclindly about its rotational center of axis. Generally when setting the distance larger between the two bearings, inclined rotation of the output shaft can be prevented.
According to the above described known art, inclined rotation of the output shaft can be prevented by providing longer space between the ball bearings, however the length of an automatic transmission in axis direction has to be lengthened. Therefore, it is difficult for installing an automatic transmission into a vehicle having very limited space for the transmission.
The present invention therefore seeks to provide an output shaft supporting structure for an automatic transmission capable of shortening the length of an automatic transmission in axial direction and preventing inclined rotation of the output shaft of the automatic transmission.